Blood Vessels

Anatomy and Physiology II

BIO 232

Types of Blood Vessels

• Arteries and arterioles

• Capillaries

• Veins and venules

Blood Vessel Walls

• Tunica interna

• Endothelium

• Subendothelial layer

• Tunica media

• Smooth muscle and sheets of elastin

• Tunica externa (adventitia)

• composed of loosely woven collagen fibers

• Large vessels - vasa vasorum - network of tiny vessesl - nourish external tissues of the vessels wall

Generalized Vessels Structure

Arterial System

• Elastic arteries - thick-walled near the heart

• Muscular arteries - more distal - deliver to specific organs

• Arterioles - smallest arteries - barely visible to the naked eye

Capillaries

• Arterioles branch into capillaries

• One cell thick walls

• Capillary beds - in all areas of the body

• Where the exchange of nutrients and waste takes place

• O₂ and nutrients diffuse into tissue fluid

• CO₂ diffuses into capillary

Capillary Beds

Capillary Beds

Venous System

Blood Pressure

• Pressure which blood exerts against the wall of a blood vessel

• Sphygmomanometer

• Systolic pressure - highest arterial pressure

• During ejection of blood by the heart

Blood Pressure

• Sphygmomanometer

• Diastolic - lowest arterial pressure

• While ventricles are relaxing

• Normal BP - 120/80

• At brachial artery of arm

Measuring Blood Pressure

Movement of Blood Through Veins and Venules

• Due to skeletal muscle contraction

• Contraction puts pressure against weak wall of veins

• Blood moves past valve - can’t return

Movement of Blood Through Veins and Venules

• Blood flow gradually increases in venous system

• Bp lowers in chest cavity during inspiration

• Helps flow of venous blood in to the chest cavity

Movement of Blood Through the Body

Pulmonary Circulation

Systemic Circulation

Schematic: Major Arteries

Major Arteries

Schematic: Arteries of Head, Neck & Brain

Arteries of Head, Neck & Brain

Schematic: Arteries of Upper Limbs & Thorax

Arteries of Upper Limbs & Thorax

Arteries of the Abdomen

Schematic: Arteries of the Pelvis & Lower Limb

Arteries of the Pelvis & Lower Limb

Schematic: Major Veins of the Systemic Circulation

Major Veins of the Systemic Circulation

Schematic: Venous Drainage of Head, Neck and Brain

Venous Drainage of Head, Neck and Brain

Schematic: Veins of the Upper Limb and Shoulder

Veins of the Upper Limb and Shoulder

Schematic: Veins of the Abdomen

Veins of the Abdomen

Schematic: Veins of the Lower Limb

Veins of the Lower Limb